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102 lines
2.9 KiB
102 lines
2.9 KiB
/* |
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Copyright 2016 The Kubernetes Authors. |
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Licensed under the Apache License, Version 2.0 (the "License"); |
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you may not use this file except in compliance with the License. |
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You may obtain a copy of the License at |
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http://www.apache.org/licenses/LICENSE-2.0 |
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Unless required by applicable law or agreed to in writing, software |
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distributed under the License is distributed on an "AS IS" BASIS, |
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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See the License for the specific language governing permissions and |
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limitations under the License. |
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*/ |
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package cache |
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import ( |
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"sync" |
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"time" |
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"github.com/hashicorp/golang-lru" |
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) |
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// Clock defines an interface for obtaining the current time |
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type Clock interface { |
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Now() time.Time |
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} |
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// realClock implements the Clock interface by calling time.Now() |
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type realClock struct{} |
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func (realClock) Now() time.Time { return time.Now() } |
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// LRUExpireCache is a cache that ensures the mostly recently accessed keys are returned with |
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// a ttl beyond which keys are forcibly expired. |
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type LRUExpireCache struct { |
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// clock is used to obtain the current time |
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clock Clock |
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cache *lru.Cache |
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lock sync.Mutex |
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} |
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// NewLRUExpireCache creates an expiring cache with the given size |
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func NewLRUExpireCache(maxSize int) *LRUExpireCache { |
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return NewLRUExpireCacheWithClock(maxSize, realClock{}) |
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} |
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// NewLRUExpireCacheWithClock creates an expiring cache with the given size, using the specified clock to obtain the current time. |
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func NewLRUExpireCacheWithClock(maxSize int, clock Clock) *LRUExpireCache { |
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cache, err := lru.New(maxSize) |
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if err != nil { |
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// if called with an invalid size |
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panic(err) |
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} |
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return &LRUExpireCache{clock: clock, cache: cache} |
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} |
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type cacheEntry struct { |
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value interface{} |
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expireTime time.Time |
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} |
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// Add adds the value to the cache at key with the specified maximum duration. |
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func (c *LRUExpireCache) Add(key interface{}, value interface{}, ttl time.Duration) { |
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c.lock.Lock() |
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defer c.lock.Unlock() |
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c.cache.Add(key, &cacheEntry{value, c.clock.Now().Add(ttl)}) |
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} |
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// Get returns the value at the specified key from the cache if it exists and is not |
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// expired, or returns false. |
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func (c *LRUExpireCache) Get(key interface{}) (interface{}, bool) { |
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c.lock.Lock() |
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defer c.lock.Unlock() |
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e, ok := c.cache.Get(key) |
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if !ok { |
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return nil, false |
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} |
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if c.clock.Now().After(e.(*cacheEntry).expireTime) { |
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c.cache.Remove(key) |
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return nil, false |
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} |
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return e.(*cacheEntry).value, true |
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} |
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// Remove removes the specified key from the cache if it exists |
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func (c *LRUExpireCache) Remove(key interface{}) { |
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c.lock.Lock() |
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defer c.lock.Unlock() |
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c.cache.Remove(key) |
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} |
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// Keys returns all the keys in the cache, even if they are expired. Subsequent calls to |
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// get may return not found. It returns all keys from oldest to newest. |
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func (c *LRUExpireCache) Keys() []interface{} { |
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c.lock.Lock() |
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defer c.lock.Unlock() |
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return c.cache.Keys() |
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}
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